Several systems of operating and locking mechanisms for railroad switches or "points" exist in various different countries and depending on the functions that are to be performed, in particular on whether the switch is capable of being burst open or "trailed". A switch which is capable of being trailed is one which, when used as a trailing switch, i.e. when approached from the direction having two tracks leading to a single track, passes traffic, without damage, coming from the track which does not correspond to the direction in which the switch is set, with the switch then being displaced by axle thrust. When a switch is approached by traffic coming from the single track and going towards one of the plurality of different tracks, the switch is said to be a facing switch. A switch includes two moving blades, referred to as a right point blade and as a left point blade. The terms "right" and "left" correspond to the positions of the point blades as seen when the switch is approached as a facing switch. One of the blades touches its corresponding backing rail, while the other blade is at a distance from its backing rail.
French switches are not trailable, whereas the switches on German lines are trailable. French switches which are used as trailing switches only or which are used as facing switches at speeds not exceeding 40 km/h, have a motor system including an guide plate and drive wheel system internal to the motor for locking the switch in each of its two positions. For switches used as facing switches at speeds in excess of 40 km/h, French railways make use, in addition, of an external, direct-action locking system for each blade individually, with such locking systems being known in France as "carter-coussinet" locks. These systems have only one drive rod actuating both the right and the left point blades.
German switches are trailable. One prior operating mechanism with internal locking includes an outlet shaft provided with two special gear wheels each meshing with the rack of a corresponding drive rod.
One of the drive rods is connected to the right point blade and the other is connected to the left point blade. The touching blade is locked by means of a locking bar which penetrates, at the end of outlet shaft rotation and at the end of drive rod displacement, in a notch provided in the drive rod of the touching blade. The mechanism is reversible when trailed, by acting on the non-locked non-touching blade which is held in place by a force from a torque limiter.
The object of the present invention is to provide a modular switch-operating device which is capable of being adapted to all kinds of function: trailable or not trailable, and regardless of the operating strokes of the blades. Said device is much simpler than the system having internal guide plate and drive wheel locking, or external locking by means of case-chair locks, or than the German trailable systems having special gear wheels and racks used with locking bars and notches. Finally, it is more robust and it provides greater safety than any existing system.